Fluoride varnish is a highly concentrated form of fluoride which is applied to the tooth's surface, by a dentist, dental hygienist or other health care professional, as a type of topical fluoride therapy. It is not a permanent varnish but due to its adherent nature it is able to stay in contact with the tooth surface for several hours. It may be applied to the enamel, dentin or cementum of the tooth and can be used to help prevent decay, remineralize the tooth surface, and to treat dentine hypersensitivity.
Fluoride-containing varnishes were originally developed some 50 years ago as a material for application by dentists to control dentinal hypersensitivity (i.e., pain to temperature changes and touch) in patients by occluding exposed dentinal tubules. In the 1960's scientists in Europe began adding 5% sodium fluoride to the varnishes to enhance their activity by precipitating calcium fluoride on the exposed tubules along with the varnish. Additional clinical studies in Europe demonstrated that these fluoride-containing varnishes also were effective for the prevention of dental caries through the release of fluoride even though their retention on the enamel surface was generally less than 24 hours. As a result of these studies fluoride varnishes are now used throughout the world for both caries prevention and the treatment of dentinal hypersensitivity.
The effectiveness of a topical fluoride (such as a varnish) is primarily a function of the amount of fluoride uptake that can be achieved in previously demineralized areas. Fluoride uptake is affected by the concentration of fluoride in the formula, the amount of time that the varnish is in contact with the demineralized area, and the ability of the varnish to induce migration of the fluoride from the varnish to the dental tissue.
With respect to the concentration of fluoride in the varnish, increased concentrations of fluoride also come with increased risks of dental fluorosis. This risk is especially pronounced and concerning for pediatric patients. Accordingly, simply providing a higher concentration of fluoride in the varnish is not always desired nor inherently superior.
Fluoride varnish is composed of a high concentration of fluoride in a fast drying (or curing), alcohol and rosin based solution. Existing varnishes are known to have 5.0% sodium fluoride. The rosin base is made of pine tree origin (e.g. colophonium or a derivative thereof). This rosin provides allergic responses in some patients. Additionally, the rosin has a yellow tint. When applied to teeth, this yellow tint is undesirable and unsightly. More recently derivatized (hydrogenated and other) versions have become readily available and used frequently. These varnishes have little color.
Additionally, many existing varnishes, when applied, have a film thickness that is detectable to a patient. This thickness is noticeable and objectionable to the touch of the tongue. In addition, most existing varnishes are organoleptically unacceptable, especially for pediatric patients.
Existing varnishes that contain sodium fluoride contain little or no water (<5%). Since the fluoride is not easily soluble in these formulas, the fluoride normally settles and precipitates in these formulas. Sodium fluoride is an inorganic chemical compound that is soluble in water. Compositions such as consumer use dentifrices and oral rinses as well as professional use foams and gels containing fluoride contain water. These embodiments allow the fluoride to be evenly dispersed and therefore provide uniform deposition onto tooth surfaces. However, since these compositions begin breaking down immediately when introduced into the oral cavity, long term retention is not possible.
The physical irritants of discoloration and objectionable feel are factors that tend to lead patients to reducing the amount of time that the varnish is permitted to act. In the case of the yellowing tint, this reduces patient likelihood to use the product in the first place and also increases the likelihood that the varnish will be prematurely removed. Similarly, the physical uncomfortability from film thickness increases the likelihood that the varnish will be removed prematurely, either voluntarily or through increased friction from being rubbed by the tongue.
Existing varnishes also suffer from separation of their ingredients during storage. Fluoride particles settle out of the mixture creating a non-homogeneous paste. U.S. Pat. No. 7,563,833 to Orlowski recognizes the difficulty in retaining fluoride salts in suspension in dental varnish. Typically, fluoride varnishes are now marketed in unit dose packages that are mixed by stirring and immediately applied with a small brush covering all of the tooth surfaces. This mixing is required due to the settling out of the ingredients. Patients are instructed not to brush their teeth for at least 4 hours (to prolong retention of the varnish) and are advised that the varnish will be gone within 24 hours or less.
Accordingly, what is needed is a varnish that does not induce a pine allergy, does not impart an unsightly yellow tint to the dental tissue, has acceptable taste properties, is of a thickness that is unnoticeable, has a fluoride concentration that reduces likelihood of dental fluorosis, has a prolonged retention time on the dental tissue, resists settling out of ingredients, and provides superior fluoride release and uptake in tooth tissue.
Additional features of the present disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of the presently perceived best mode of carrying out the disclosure.